This invention relates to apparatus for forming protuberances on a line and more particularly, but not by way of limitation, to apparatus for manufacturing string of the type disclosed in my co-pending U.S. patent application Ser. No. 214,188 filed Dec. 8, 1980.
Heretofore, substantially smooth-surfaced materials have been used for stringing tennis rackets and the like. With such smooth-surfaced materials, engagement of a ball or other object by the racket is generally by means of the angular relationship between the racket and the ball and by means of friction between the surface of the string and the surface of the ball. Such smooth-surfaced line provides little mechanical engagement, other than the frictional engagement, with the ball for assisting in spinning the ball when the string engages the ball.
However, because it is at times advantageous to impart various types of spin to a tennis ball or the like during the playing of a game, for example, there is a need for a suitable string which provides or increases the mechanical connection between the ball and the line comprising the network of the racket so that improved spin can be imparted to the ball. Because there is the need for such a string, there is the additional need for an apparatus for manufacturing such a string.